This section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present techniques. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present techniques. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.
Systems that deliver power from a driver, such as a motor, gas turbine, steam turbine, hydraulic turbine, gearbox or similar device, to one or more other components, such as a compressor, pump, gearbox or similar device, typically include an object for power delivery such as a shaft. The shaft has a direction of rotation about an axis that results in normal operation of the power delivery system. In some situations, failure of a valve, check valve, non-return valve or other component will result in the shaft reversing its direction of rotation, especially following the shutdown of a driver. Reverse rotation can cause extensive damage to a machinery drive train, including as examples seal failure, bearing damage (e.g. if lubrication system is not ready), reverse power (generator units) and in some cases, over-speed and catastrophic unit failure. The ability to detect a direction of rotation can be important to potentially avoid significant damage to equipment by detecting when the direction of rotation reverses and possibly taking further action.
Conventional techniques for detection of reverse rotation use multiple sensors and/or complex configurations of reference devices on/attached to a shaft and/or uses pulse/reference counting devices/mechanisms (e.g. Kurumado in U.S. Pat. No. 8,018,224, Ishikawa in EP1878897, or Rupp in EP1070964). Other conventional techniques include use of an audible device such as a whistle to warn of a reverse rotation of a pump, fan or other rotating equipment. Such an audible device may be mounted onto or integrated with the pump, fan or other rotatable object and make an audible signal or alert sound if and only if the pump, fan or other rotatable object is rotating in a direction that is opposite its normal direction of rotation. The volume of the signal or alert sound is set to be sufficient to identify the reverse rotation to plant personnel so that corrective action may be executed. These systems may be ineffective and can be costly to implement and/or not amenable to retrofitting onto existing machinery for detection of reverse rotation. There is therefore a need for improved systems that accurately determine the direction of rotation in ways that reduce cost and complexity.